The present invention relates to roofing systems.
Rigid foam panels are currently available for use as an insulating underlayment in roof construction. Typically these are 4xe2x80x2 by 8xe2x80x2 (1.22 m by 2.44 m) panels 1.5xe2x80x3 (3.8 cm) thick made of a 1.6 pound per cubic foot polyurethane foam with a tar paper top layer. Such a material is not crush resistant enough to be used as a roof surface material and can also be easily punctured.
It is therefore an object of the present invention to provide a sturdy, weatherproof, seamless roofing system that uses rigid foam boards or panels to create a seamless waterproof roof.
The roofing panels of this invention differ from the prior art underlayment product in several respects. The panels of this invention are:
a) made of a denser polyurethane foam (approximately 3 pounds per cubic foot) and,
b) include an integral top layer of non-woven 250 gram polyester fabric that is saturated by the foam during manufacture by the laminator in a controlled factory environment.
The higher density affords more crush resistance, while the well bonded top layer resists punctures and provides a better adhesion surface for elastomeric top coats.
The roofing panels are bonded to roof substrate with low rise foam polyurethane adhesive which seeps through loose tongue-in-groove joints to form a blob at the top, which is shaved off and covered with a fabric top layer.
After the adhesive cures, a very secure bond between the panels results.
The low rise foam adhesive is a two-part mixture that has distinct phases after mixing. By varying the formulations of the two parts, the xe2x80x9ccream timexe2x80x9d (i.e.xe2x80x94to achieve the consistency of shaving cream) as well as the xe2x80x9ctack freexe2x80x9d time can be controlled.
The panels are placed on the foam just after cream consistency and well before tack-free time so that the foam rises through the joints. After the adhesive cures to a solid consistency, the blobs are removed from all of the joints. This is typically accomplished by grinding using a disk pad grinder.
The roof is finished by applying a layer of waterproof elastomeric coating which covers the entire surface creating a monolithic structure.